This picture taken on March 28, 2016 shows the remaining structure of a factory building buried at a mud volcano area in Sidoarjo, East Java. A mud volcano that erupted in central Indonesia a decade ago and swallowed entire villages is still oozing its all-consuming sludge, but for some entrepreneurial locals it has provided an unlikely business opportunity. "Mud tourism" is booming, as visitors flock to see rooftops poking above the giant bubbling lake, life-size statues made of mud and haunting memorials to one of the countrys worst environmental disasters. / AFP PHOTO / ADEK BERRY / To go with AFP story 'Indonesia-science-mud-volcano-tourism',FEATURE by Nick PerryADEK BERRY/AFP/Getty Images

(FILES) This file photo taken on September 11, 2013 shows the logo of social networking website 'Twitter' is displayed on a computer screen in London. Twitter plans to let people fire off links or pictures without eating into the 140-character limit set for posts at the one-to-many messaging service, Bloomberg reported on May 16, 2016. The change could take place by the end of this month, according to a Blomberg report that cited someone familiar with the matter. / AFP PHOTO / LEON NEALLEON NEAL/AFP/Getty Images

Students walk past the entrance to the University of Johannesburg auditorium in Johannesburg, South Africa, on May 16, 2016, after it was firebombed in what is believed to be part of an "organised set of attacks" targeting educational institutions. The overnight arson attack at the University of Johannesburg caused about 100 million rand (USD 640,000) damage, destroying an auditorium, computer laboratories and equipment. No arrests have yet been made over the attack, which follows months of sporadic violence, protests and clashes at universities around South Africa. A statement from the university said arsonists had "fire bombed" the 1,000-seater auditorium as well as computer laboratories full of equipment. / AFP PHOTO / MUJAHID SAFODIENMUJAHID SAFODIEN/AFP/Getty Images

A police cordon is seen near the entrance to the University of Johannesburg auditorium in Johannesburg, South Africa, on May 16, 2016, after it was firebombed in what is believed to be part of an "organised set of attacks" targeting educational institutions. The overnight arson attack at the University of Johannesburg caused about 100 million rand (USD 640,000) damage, destroying an auditorium, computer laboratories and equipment. No arrests have yet been made over the attack, which follows months of sporadic violence, protests and clashes at universities around South Africa. A statement from the university said arsonists had "fire bombed" the 1,000-seater auditorium as well as computer laboratories full of equipment. / AFP PHOTO / MUJAHID SAFODIENMUJAHID SAFODIEN/AFP/Getty Images

The entrance to the University of Johannesburg auditorium is pictured on May 16, 2016 in Johannesburg, South Africa, after it was firebombed in what is believed to be part of an "organised set of attacks" targeting educational institutions. The overnight arson attack at the University of Johannesburg caused about 100 million rand (USD 640,000) damage, destroying an auditorium, computer laboratories and equipment. No arrests have yet been made over the attack, which follows months of sporadic violence, protests and clashes at universities around South Africa. A statement from the university said arsonists had "fire bombed" the 1,000-seater auditorium as well as computer laboratories full of equipment. / AFP PHOTO / MUJAHID SAFODIENMUJAHID SAFODIEN/AFP/Getty Images

A man stands near the entrance to the University of Johannesburg auditorium in Johannesburg, South Africa, on May 16, 2016, after it was firebombed in what is believed to be part of an "organised set of attacks" targeting educational institutions. The overnight arson attack at the University of Johannesburg caused about 100 million rand (USD 640,000) damage, destroying an auditorium, computer laboratories and equipment. No arrests have yet been made over the attack, which follows months of sporadic violence, protests and clashes at universities around South Africa. A statement from the university said arsonists had "fire bombed" the 1,000-seater auditorium as well as computer laboratories full of equipment. / AFP PHOTO / MUJAHID SAFODIENMUJAHID SAFODIEN/AFP/Getty Images

Visitors look at projections of the installation piece "Flowers and People, Cannot be Controlled but Live Together" at the teamLab Islands: Dance! Art Museum, Learn & Play! Interactive Theme Park in Bangkok on May 16, 2016. teamLab are a group of Japanese technology, engineering, architecture and graphic design experts who exhibit digital installations worldwide. / AFP PHOTO / LILLIAN SUWANRUMPHA / RESTRICTED TO EDITORIAL USE - MANDATORY MENTION OF THE ARTIST UPON PUBLICATION - TO ILLUSTRATE THE EVENT AS SPECIFIED IN THE CAPTIONLILLIAN SUWANRUMPHA/AFP/Getty Images

People take pictures with the installation piece "Flowers and People, Cannot be Controlled but Live Together" at the teamLab Islands: Dance! Art Museum, Learn & Play! Interactive Theme Park in Bangkok on May 16, 2016. teamLab are a group of Japanese technology, engineering, architecture and graphic design experts who exhibit digital installations worldwide. / AFP PHOTO / LILLIAN SUWANRUMPHA / RESTRICTED TO EDITORIAL USE - MANDATORY MENTION OF THE ARTIST UPON PUBLICATION - TO ILLUSTRATE THE EVENT AS SPECIFIED IN THE CAPTIONLILLIAN SUWANRUMPHA/AFP/Getty Images